Bone density scan result-matched orthopedic implants and methods of use

ABSTRACT

A method of treating a patient in need of an orthopedic implant is described. The method includes obtaining the T-score or bone density of the patient&#39;s native bone at a site of implantation, said T-score or bone density being determined by a DEXA scan or other means of determining a T-score or bone density. The method further includes selecting an orthopedic implant that has about the same density as the native bone at the site of implantation, and implanting the orthopedic implant at the site of implantation.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 17/190,968, filed on Mar. 3, 2021, which is acontinuation-in-part of U.S. patent application Ser. No. 16/995,256,filed on Aug. 17, 2020, which is a continuation of U.S. patentapplication Ser. No. 15/840,697, filed on Dec. 13, 2017, now U.S. Pat.No. 10,779,954, which claims priority from U.S. Provisional PatentApplication Ser. No. 62/433,345 filed Dec. 13, 2016, all of which areincorporated herein by reference in their entirety.

BACKGROUND

This invention relates generally to the field of orthopedic surgeryinvolving orthopedic implants to correct or repair damaged bones,cartilage, vertebral discs and other musculoskeletal structures. Suchsurgery may include implants such as interbody cage implants (fusion ornon-fusion) for spinal surgery to replace damaged or diseased vertebraldiscs, interspinous fixation implants, full or partial knee replacementimplants, full or partial hip replacement implants and the like.

A bone density test is used to measure bone mineral content and density(sometimes referred to herein as “BMD”). It may be done using X-rays,dual-energy X-ray absorptiometry (DEXA or DXA), or a special CT scanthat uses computer software to determine bone density of the hip orspine. For various reasons, the DEXA scan is considered the “goldstandard” or most accurate test.

This measurement tells the healthcare provider whether there isdecreased bone mass. This is a condition in which bones are more brittleand prone to break or fracture easily. A bone density test is usedmainly to diagnose osteopenia and osteoporosis. It is also used todetermine a patient's future fracture risk.

In patients scheduled to undergo orthopedic surgery, bone quality in thearea of surgical intervention and implantation affects the safety andlongevity of the prosthetic implant. For example, in patients undergoingjoint arthroplasty of the hip, the bone quality around the joint affectsthe safety and failure rate and useful life span of the implant. BMD canalso affect strategies employed in spinal fusion in osteoporotic spines.

BMD is a clinical marker for bone strength. Bone mineral density variesamong different body regions and also varies as a result of age,disease, injury, general health, weight, demographic, and use of certainmedications or hormones.

Although BMD at the site of intervention is correlated with long-termresults, bone density scans of the diseased or damaged site are notalways performed and even when they are performed, they do not affectthe course of treatment in terms of the specific implant that is used.Thus, there is a one size fits all standard of care when it comes toorthopedic implants as they relate to the bone density of the areasurrounding the implant.

The gold standard for bone densitometry or bone density scans is thedual energy x-ray absorptiometry (“DEXA” or “DXA”) scan. A DEXA scan isa means of measuring bone density by directing two x-ray beams withdifferent energy levels at the patient's bone at the diseased or injuredsite or the site of diagnosis for age-related routine scans to determineBMD. When soft tissue absorption is subtracted out, the BMD can bedetermined from the absorption of each beam by the bone. DEXA scans arethe most widely used and most thoroughly studied bone densitymeasurement technology for determining the density of bone.

Bone density scans prior to an orthopedic implant are not always thestandard of care. For example, in one study, orthopedic surgeons wereasked if BMD is important to them in performing hip arthroplasty (MaierG S, Kolbow K, Djorde L, Maus U. The Importance of Bone Mineral Densityin Hip Arthroplasty: Results of a Survey Asking Orthopaedic Surgeonsabout Their Opinions and Attitudes Concerning Osteoporosis and HipArthroplasty. Adv. In Orthopedics. 2016, Article ID 8079354). 72% of allasked orthopaedics reported to use cementless implants as a standard inhip arthroplasty, and over 60% reported that low BMD is a reason toreconsider operation strategies, such as using cement if the patient haslow BMD. However, only 4% performed BMD measurement preoperatively.

Another example where BMD is an important factor, albeit one that is nottypically considered, in patient treatment is spinal fusion implants,including those that employ PEEk or titanium cages. Especially in olderpatients with osteoporosis, low BMD at the site of fusion is associatedwith poor fusion rate and bone stability. Various interventions havebeen proposed to address this problem, but most interventions focussimply on poor screw fixation or screw loosening and fixation failure.Many techniques have been employed to enhance the pullout strength ofthe pedicle screws that fix cages to the vertebrae. The preparation forscrew hole or minimization of tapping hole can affect the pulloutstrength in osteoporotic bone and, although the anatomical constraintsvary with patients, bigger and longer screws have been used to improvefixation to fragile bones. Other solutions involve the angulation of thescrews and screw positioning in areas of higher BMD, either of which mayincrease pullout strength. These techniques may enhance fixation, butthey still don't address the core problem of implant failure thatresults from poor bone BMD around the implant.

In fact, the current standard of care considers BMD around the site ofintervention mainly as a factor to determine whether or not to perform aprocedure, and sometimes, as discussed above, BMD is used as a factor toalter fixation methods, such as the screws. Otherwise, BMD is mostlyused as a means of diagnosing the progression of osteoporosis in olderpatients, and is not a factor in the use and type of orthopedicimplants.

Clinically, stiffening of the functional spinal unit (FSU) is aconsequence of surgical intervention for fusion. While such a conditionis unavoidable, Applicants believe that more focus is needed ondeveloping a mechanical configuration that will provide sufficientstability yet not result in stress shielding due to an overly stiffconstruct. For example, as it relates to titanium cage interbody spinalfusion implants, the modulus of elasticity for trabecular bone has beenreported to be approximately 0.10 GPa, while titanium displays a modulusof 110 GPa, and reinforced PEEK has a modulus of approximately 18 GPa.In short, the implants and the surrounding bone don't match, and therehas been no focus in the clinic or the scientific literature on thismismatch and whether it leads to a higher than necessary incidence offailure in implants over time.

For example, in the case of spinal fusion, Applicants believe thatinterbody cage stiffness can affect surgical outcomes, particularly inosteoporotic bone. Unwanted subsidence or collapse of the vertebralendplates is an unfortunate result that happens too frequently. Thepatient's bone density scan is able to reveal the level of osteoporosisin the subject patient but no bone scan density result-matched interbodycage with semi-customized interbody implant is available at the presenttime, nor has such a matched method of intervention been contemplateduntil the present invention. Certainly there has been no effort to matcha patient's DEXA scan with an implant that closely approximates the DEXAscan so that the implant and the surrounding bone at the site ofintervention are similar in density. Nor has such a method beenconsidered as a means of improving long-term outcome for patients withorthopedic implants, such as interbody spinal fusion cage implants orhip implants, among others.

There is a need to improve results in orthopedic implants. There is aneed to customize implants based on the health and strength of the boneat the site of intervention. There is a need to improve fusion andminimize failure at the site of fusion. There is a need to deliverimplants that match the mechanics of the surrounding tissue so that thenew and the old are adapted to one another and one is not prone to causethe failure of the other. These are needs that have not been addresseduntil now.

SUMMARY

One object of the invention is to provide a spine surgery fusion productthat has variable stiffness designs in order to match patients' bonedensity and be as close as possible to the modulus of the patient's ownbone modulus. The modulus of elasticity variation of one embodiment ofthe current invention can be achieved by making the design hollow tocreate a “soft-cage” that has lower, medium or higher material density,and the various optional densities can be used to best match the implantto the bone at the site of intervention.

In various embodiments, the implants described herein can bemanufactured from implantable metal, plastic, reinforced plastic,titanium, titanium cobalt, stainless steel, cobalt-chromium alloys,titanium and cobalt mixed metal, ceramic, PEEK or carbon fiber. Theinterbody cages described herein can be manufactured employing wellknown traditional manufacturing methods or newer methods such as 3-Dprinting.

In one embodiment, a kit for orthopedic surgical procedures is provided.The kit has two, three, four or more orthopedic implants of the sametype. In one embodiment, there are two implants, and one of the implantshas a first density that is less than the density of the second implant.In another embodiment there are three implants. The first implant has afirst density, the second implant has a second density that is lowerthan the first density, and the third implant has a third density thatis lower than the first and second densities. Other than the density ofthe implants, the three implants are the same in outer dimension andwill otherwise fit within the same space of a surgical site ofintervention. The kit also includes instructions for use during asurgical procedure on a patient. The instructions include the followingsteps: determine the DEXA scan T-score of the patient's native bone at asite of surgical intervention;

-   -   i. if the DEXA scan T-score of the patient's native bone is −1        or higher, then retrieve the first implant and introduce it to        the patient's native bone to the exclusion of the second and        third implants;    -   ii. if the DEXA scan T-score of the patient's native bone is        between a −2.5 and −1.0, then retrieve the second implant and        introduce it to the patient's native bone to the exclusion of        the first and third implants; and    -   iii. if the DEXA scan T-score of the patient's native bone is        lower than −2.5, then retrieve the third implant and introduce        it to the patient's native bone to the exclusion of the first        and second implants.

In one embodiment, the implants are interbody cages. In one particularembodiment, the interbody cages are for spine fusion, and in anotherembodiment, the cages are not for spine fusion. In other embodiments,the implants are femoral stems of a hip implant or acetabular componentsof a hip implant.

In another embodiment, a method of treating a patient who requiressurgical implantation of an orthopedic implant is described. The methodincludes the steps of: determining the DEXA scan T-score of thepatient's native bone at a site of surgical implantation where theimplant will be in contact with the patient's native bone; retrieve animplant that has a density that is closest to the density of thepatient's native bone at the site of surgical implantation based on theDEXA scan T-score of the patient's native bone; and implanting theretrieved implant in the patient. In one embodiment, the implants areinterbody cages, which may or may not be for spine fusion. In otherembodiments the implants are femoral stems of a hip implant oracetabular components of a hip implant.

In another embodiment, an interbody cage implant that has about the samedensity as natural bone that has a T-score of −1.0 or higher as measuredby a DEXA scan is described. The interbody cage implant has anidentifier that identifies it as having a density that is about the sameas natural bone having a T-score above −1.0. The interbody cage implantcan have a density of about 1.10 g/cm³ or greater. In one embodiment,the identifier can be the color green, and the whole cage can be greenor just a portion of the cage can be green. In another embodiment, theinterbody cage implant is frameless. In yet another embodiment, theidentifier is visible in an x-ray image of the implant.

In another embodiment, an interbody cage implant that has about the samedensity as natural bone that has a T-score of between −2.5 and −1.0 asmeasured by a DEXA scan is described. The interbody cage implant has anidentifier that identifies it as having a density that is about the sameas natural bone having a T-score of between −1.5 and −1.0. The interbodycage implant can have a density of between about 0.90 g/cm³ and about1.10 g/cm³. In one embodiment, the identifier can be the color yellow,and the whole cage can be yellow or just a portion of the cage can beyellow. In another embodiment, the interbody cage implant is frameless.In yet another embodiment, the identifier is visible in an x-ray imageof the implant.

In another embodiment, an interbody cage implant that has about the samedensity as natural bone that has a T-score lower than −2.5 as measuredby a DEXA scan is described. The interbody cage implant has anidentifier that identifies it as having a density that is about the sameas natural bone having a T-score below −2.5. The interbody cage implantcan have a density of below about 0.90 g/cm³. In one embodiment, theidentifier can be the color red, and the whole cage can be red or just aportion of the cage can be red. In another embodiment, the interbodycage implant is frameless. In yet another embodiment, the identifier isvisible in an x-ray image of the implant.

In yet another embodiment, a method of treating a patient in need of anorthopedic implant is described. The method includes obtaining theT-score or bone density of the patient's native bone at a site ofimplantation, said T-score or bone density being determined by a DEXAscan or other means of determining a T-score or bone density. The methodfurther includes selecting an orthopedic implant that has about the samedensity as the native bone at the site of implantation, and implantingthe orthopedic implant at the site of implantation.

Other objects and advantages of the present invention will becomeapparent from the following descriptions, taken in connection with theaccompanying drawings, wherein, by way of illustration and example,various embodiments of the present invention are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and includeexemplary embodiments to the invention, which may be embodied in variousforms. It is to be understood that in some instances various aspects ofthe invention may be shown exaggerated or enlarged to facilitate anunderstanding of the invention.

FIG. 1 is a perspective view of a kit of three interbody cage implants.

FIG. 2 is a perspective view of one of the interbody cage implants fromthe kit of FIG. 1 with anchors and an anchor plate.

FIG. 3 is a side view of the interbody cage implant of FIG. 2.

FIG. 4 is a perspective view of an anchor used in the interbody cageimplant of FIG. 2.

FIG. 5 is a perspective view of an anchor plate used to secure theanchors of the interbody cage implant of FIG. 2.

FIG. 6 is a top side view of the anchor plate of FIG. 5.

FIG. 7 is a DEXA Scan T score chart of the prior art.

FIG. 8 provides side and top views of an embodiment of frameless,lattice structured interbody cage implants with three different levelsof densities and porosities corresponding with different DEXA Scan Tscores or different BMDs.

DETAILED DESCRIPTION

Exemplary embodiments of the invention are shown in the accompanyingfigures and described below.

A bone mineral density (BMD) test provides a snapshot of bone health byproviding a value associated with bone density. The more dense the bone,the healthier and stronger it is. The test is typically performed toidentify osteoporosis, determine risk for fractures (broken bones), andmeasure response to osteoporosis treatment. It is not presently used todetermine the appropriate density of an orthopedic implant for a patientundergoing an orthopedic surgical procedure requiring an implant.

The most widely recognized BMD test is called a central dual-energyx-ray absorptiometry, or central DEXA scan. The DEXA scan can measurebone density at the hip, spine and other bones. A DEXA scan measures BMDand compares it to that of an established norm or reference standard togive the patient a DEXA Scan score. The DEXA scan score is called aT-score, which is a value that compares the patient to an ideal or peakbone mineral density of a healthy 30-year old adult. A score of 0 meansthe BMD is equal to the norm for a healthy young adult. Differencesbetween the patient's BMD and that of the healthy young adult norm aremeasured in units called standard deviations (SDs). The more standarddeviations below 0, indicated as negative numbers, the lower thepatient's BMD, meaning the less dense the bone. A DEXA scan T-scorebetween +1 and −1 is considered normal or healthy. A DEXA Scan T-scorebetween −1 and −2.5 indicates low BMD, although not low enough to bediagnosed with severe osteoporosis. A DEXA scan T-score of −2.5 or lowerindicates osteoporosis and means that the BMD is very low. The greaterthe negative number, the more severe the osteoporosis and the less densethe bone. Thus, when the DEXA scan T-score is between +1 and −1 (or ishigher than −1), the BMD of the bone is normal. When the DEXA scan scoreis between 1 and 2.5 SD below the young adult mean (−1 to −2.5 SD), thenthe BMD is lower than normal and indicates bone that is less dense thannormal bone for that location. When the DEXA scan score is 2.5 SD ormore below the young adult mean (−2.5 SD or lower) this indicates bonedensity that is significantly below normal for bone in that location andis an indicator of osteoporosis. These scores are typically associatedwith a DEXA scan chart, such as the one shown in FIG. 7, in which thenormal range of +1 to −1 (or greater than −1) is represented in green,the below normal range of −1 to −2.5 is represented in yellow, and thevery low range below −2.5 indicating osteoporosis is represented in red.This is a standard method of depicting the DEXA scan T-score in themedical community.

DEXA scan T-scores of the spinal column are typically matched to BMD asfollows. BMD in g/cm³ of about 1.10 and higher are associated with anormal bone density and are therefore given a DEXA scan T-score of atleast −1 or higher (meaning 0, +1 and higher), i.e., in the green range.BMD in g/cm² of about 0.90 to about 1.10 are associated with low bonemass and are therefore given a DEXA scan T-score of between −1 and −2.5,i.e., in the yellow range. Finally, BMD below about 0.90 g/cm³ areassociated with very low bone mass and osteoporosis and are thereforegiven a DEXA scan T-score of below 2.5, i.e., in the red range.

The present invention provides methods of treatment and orthopedicimplant kits that allow physicians to best match the implant with theirpatient's DEXA Scan T-score such that the implant that most closelyapproximates the density of the bone at the site of implantationrelative to other implants is the one that is implanted to the exclusionof the other implants of the same type. When given the choice of two,three or more implants of the same type that only differ by density,surface area, and porosity, the surgeon can choose the implant that mostclosely approximates the patient's native bone at the site ofimplantation based on the patient's DEXA Scan T-score.

One embodiment of the invention is illustrated in FIG. 1. FIG. 1 showsthree interbody spinal cage implants that are part of a kit 1. Theinterbody spinal cage implants may be fusion implants may or may not befusion implants. Kit 1 may have two interbody cage implants instead ofthree. Kit 1 may have four or more interbody cage implants instead ofthree. Interbody cage implants are well known in the art and they comein various sizes and shapes to fit within the lumbar, thoracic orcervical spine. One example of an interbody cage is the Discovery™minimally invasive cervical interbody spinal fusion cage made by AuroraSpine. There are many other examples made by many other manufacturersfrom many different shapes, sizes and materials.

In one embodiment, kit 1 contains cage 10, cage 11, and cage 12(although in other embodiments it may contain only cage 10 and 11, cage10 and 12, or cage 11 and 12. It can also contain an inserter 13 forinserting cages 10, 11 or 12 into the disk space in between twovertebral bodies in the spinal column of a patient, as well asinstructions for use (not shown). Kit 1 may also include one or moresizers to determine the correct size of interbody cage implant to insertinto the disk space. Kit 1 may also include graft material that ispacked into the hollow space B in the center of cages 10, 11 or 12. Eachof cages 10, 11, and 12 have outer dimensions that are virtuallyidentical, meaning they are the same or about the same height, width,and depth. However, they are not the same weight, and they do not havethe same density, porosity or amount of surface area. Cage 10 is theheaviest of the three cages, has the least porosity, the least surfacearea and the most density. Cage 11 weighs less than cage 10 but morethan cage 12. Cage 11 has more porosity, more surface area, and lessdensity than cage 10 but less porosity, less surface area and moredensity than cage 12. Cage 12 weighs less than both cage 10 and cage 11.Cage 12 has more porosity, more surface area, and less density than bothcages 10 and 11. Cages 10, 11 and 12 can be manufactured fromimplantable metal, plastic, reinforced plastic, titanium, titaniumcobalt, stainless steel, cobalt-chromium alloys, titanium and cobaltmixed metal, ceramic, PEEK or carbon fiber, or combinations of any ofthe above. In one embodiment, they are manufactured from titanium. Theweight, density, surface area, and porosity of the three cages differsas a result of the number and positioning of various hollow channels Athrough the cages, which run through the solid surfaces of the cages.The cage with the most number of hollow channels running through it hasthe most porosity, is the lightest in weight, is the lowest in density,and has the most surface area. Cage 12 has the most porosity, leastdensity, lowest weight and highest surface area among the three cages inkit 1, because it has the most number of hollow channels A runningthrough its otherwise solid body. Cage 12 therefore has the leastresistance to crush under load and is most similar to osteoporotic bonehaving a DEXA Scan T-score of −2.5 or lower (in the red range of a DEXAscan T-score) as compared to cages 11 and 10. Cage 11 has fewer hollowchannels A running through it than cage 12 but has more hollow channelsA than cage 10. Cage 11 is heavier, less porous, more dense, and hasless surface area than cage 12, but is lighter in weight, more porous,less dense, and has more surface area than cage 10. Therefore, cage 11is more dense than cage 12 but less dense than cage 10 and is mostsimilar to low density bone at the T-Score range of −1 to −2.5 (in theyellow range of a DEXA scan T-score) as compared to the other two cages10 and 12. Cage 10 has fewer hollow channels A than both cages 11 and12, and is therefore the heaviest in weight, least porous, most dense,and have the least amount of surface area of cages 10, 11 and 12 of kit1. Cage 10 has the strongest resistance to crushing under load comparedto cages 11 and 12. Cage 10 is therefore the cage among cages 10, 11 and12 that is most similar to healthy bone having a DEXA scan T-score rangeof −1 or higher (in the green range of a DEXA scan T-score) as comparedto the other two cages 11 and 12.

In another embodiment as shown in FIG. 8, cages 10 a, 11 a, and 12 aeach are formed form a lattice structure designed to simulate thelattice structure of human cancellous bone, with a similar modulus ofelasticity, and as described above, specialized to match a patient'sbone status across the BMD continuum. Cages 10 a, 11 a, and 12 a haveopen, porous structures that mimic the web-like structure of nativecancellous bone and that support osseointegration and vascularization.Cages 10 a, 11 a, and 12 a, can be frameless, as shown in FIG. 8, suchthat there is no surrounding perimeter forming a solid frame around aporous interior structure. Applicants have made the unexpected discoverythat a frame alters the modulus of elasticity of a cage, and alters themechanics of the cage even when a cage with a frame has the sameporosity and density as a cage without a frame. Cages 10 a, 11 a, and 12a correspond with cages 10, 11 and 12 in terms of their porosity anddensity, such that cage 10 a has about the same density and porosity ascage 10, cage 11 a has about the same density and porosity as cage 11,and cage 12 a has about the same density and porosity as cage 12.

Turning to cages 10 and 10 a, they have the highest density of the threesets of cages. In one embodiment, cages 10 and 10 a each have a densityof about 4.40 g/cm³, but can range from about 3.90 g/cm³ to about 5.00g/cm³ in density. In another embodiment, they each have a density ofabout 3.90 g/cm³. In another embodiment, they each have a density ofabout 3 g/cm³, but they can range from about 2 g/cm³ to about 4 g/cm³ indensity. In another embodiment, they each have a density of about 1.40g/cm³, but can range from about 1.10 g/cm³ to about 1.80 g/cm³ indensity.

Turning to cages 11 and 11 a, they each have a density that is inbetween the densities of cage 10/10 a and cages 12/12 a respectively,meaning they are less dense than cages 10 and 10 a respectively but moredense than cage 12 and 12 a respectively. In one embodiment, they eachhave a density of about 3.80 g/cm³, but range from about 3.30 g/cm³ toabout 4.20 g/cm³ in density. In one embodiment, they each have a densityof about 3.30 g/cm³. In another embodiment, they each have a density ofabout 2.00 g/cm³, but can range from about 1.00 g/cm³ to about 3.00g/cm³ in density. In another embodiment, they each have a density ofabout 1 g/cm³, but can range from about 0.90 g/cm³ to about 1.10 g/cm³in density.

Turning to cages 12 and 12 a, they each have a density that is lowerthan both cages 10 and 10 a and cages 11 and 11 a respectively. In oneembodiment, they each have a density of about 3.20 g/cm³, but range fromabout 2.50 g/cm³ to about 3.60 g/cm³ in density. In one embodiment, theyeach have a density of about 2.50 g/cm³. In another embodiment, theyeach have a density of about 1.50 g/cm³, but can range from about 1.00g/cm³ to about 2.5 g/cm³. In another embodiment, they each have adensity of about 0.80 g/cm³, but can range from about 0.60 g/cm³ toabout 0.90 g/cm³ in density.

In another embodiment, not shown in the figures, kit 1 may contain afourth cage that is still lower in density than cage 12 or 12 a, and isused to match DEXA scan T-scores that are lower than −3 suggesting notonly osteoporosis but potentially a fracture. In one embodiment, thefourth cage has a density of about 2.50 g/cm³, but can range from about2.00 g/cm³ to about 3.00 g/cm³ in density. In another embodiment, it hasa density of about 1.00 g/cm³ but can range from about 0.40 g/cm³ toabout 1.3 g/cm³ in density. In another embodiment, it has a density ofabout 0.60 g/cm³, but can range from about 0.40 g/cm³ and about 0.70g/cm³ in density. It can be formed with channels A like cages 10, 11 and12, or with a lattice structure like cages 10 a, 11 a, and 12 a.

In one embodiment, cages 10/10 a, 11/11 a and 12/12 a can have markingson them that are visible in x-ray images of the cages. The markings canbe etched into one of the outer walls of the cages, or they can be 3-Dprinted so that they are raised outwardly from one of the outer walls.In one embodiment, the markings are made from the same material as therest of the cage, but are much denser or are solid thus making themvisible in an x-ray image of the cages. In one embodiment, the markingsare identifying indicia that indicate whether the cages are the mostdense (also heaviest, least porous and least surface area), middledensity (middle heavy, middle porous and middle surface area), or leastdense (least heavy, most porous and most surface area) of the 3 cages.For example, the cages can be numbered 1 for cage 10/10 a, 2 for cage11/11 a and 3 for cage 12/12 a or the reverse. In another embodiment,their relative density/porosity/weight/surface area may be identified bya + − and = signs. In another embodiment, they can be identified by DHD(acronym for Dexa high density) for cage 10/10 a, DMD (acronym for Dexamid density) for cage 11/11 a, and DLD (acronym for Dexa low density)for cage 12/12 a. These identifiers can be etched into the cages, 3-Dprinted with the cages, or otherwise molded with raised markings orindented markings that are visible in an x-ray image taken of the cageseven after they are implanted. In one embodiment, the identifiers canhave a different density than the rest of their respective cage. Forexample, the identifiers can be solid and not forming a latticestructure, thus making them visible in an x-ray image of the cage. Theidentifiers can be on an outer wall of the cage in such a manner thatthe identifier is detectable with an x-ray scan after the cage isimplanted for future reference. Thus, when a future x-ray is taken ofthe patient, the identifier is visible in the x-ray image so that thehealthcare provider viewing the x-ray scan can see the identifier andknow which density cage is implanted into the patient. In oneembodiment, the identifiers are on the posterior outer wall 10P, 11P,and 12P of cages 10 a, 11 a, and 12 a respectively. In anotherembodiment, as shown in FIG. 8, the identifiers are on one or both ofthe lateral outer wall 10L, 11L and 12L of cages 10 a, 11 a, and 12 arespectively. In another embodiment, the identifiers are on the anteriorouter wall 10A, 11A and 12A of cages 10 a, 11 a, and 12 a respectively.In yet another embodiment, the identifiers are on all of the outer wallsof cages 10/10 a, 11/11 a, and 12/12 a. For example, cage 10/10 a canhave the marking DHD (Dexa High Density) on a lateral wall 10L, with theDHD marking being visible in an x-ray image of cage 10/10 a. Cage 11/11a can have the marking DMD (Dexa Mid Density) on a lateral wall 11L,with the DMD marking being visible in an x-ray image of cage 11/11 a.Cage 12/12 a can have the marking DLD (Dexa Low Density) on a lateralwall 12L, with the DLD marking being visible in an x-ray image of cage12/12 a.

In another embodiment, the cages may have a color painted on an area ofthe cage or the entirety of the cage. For example, cage 10/10 a may begreen, cage 11/11 a may be yellow and cage 12/12 a may be red to matchthe typical DEXA Scan color coded results. In another embodiment, eachof cages 10/10 a, 11/11 a and 12/12 a is located within a sealed packageof its own that itself has an identifier that indicates whether it isthe most dense/least porous/heaviest/lowest surface area, middledensity/porosity/weight/surface area or least dense/mostporous/lightest/highest surface area of the cages. For example, cage10/10 a may be in a sealed package that is green or has green markingson it; cage 11/11 a may be in a sealed package that is yellow or hasyellow markings on it; and cage 12/12 a may be in a sealed package thatis red or has red markings on it. The purpose of this is so that theteam of surgeons and staff that are involved in a surgical procedure caneasily identify which of the cages 10/10 a, 11/11 a, or 12/12 a theyshould use based on the DEXA scan T-score of the patient's spinal columnat the site of intervention, and they won't make a mistake by implantingthe wrong cage.

FIG. 2 shows an exemplary embodiment of a cage 12 with anchors 21 andanchor plate 40. The anchors 31 and anchor plate 40 also fit and areused with cages 10 and 11 in the same manner. Each of cages 10, 11 and12 also has a center hole B where bone graft material can be packedprior to insertion into disk space within a spinal column of a patient.Anchors 21 have the same density as the cages with which they areassociated. Anchors 21 can be made with the right amount of holes orchannels A to give the anchors the density level that matches thedensity of the cage with which they are matched and packaged. Thus,anchors 21 can have the same density as cage 10, the same density ascage 11, or the same density as cage 12. Anchors 21 that are matchedwith cage 10 in density have the least amount of holes or channelscompared to anchors 21 that are matched with cages 11 or 12. Anchors 21that are matched with cage 11 in density have fewer holes or channels Athan anchors 21 that are matched with cage 12 but more holes or channelsA than anchors 21 that are matched with cage 10. Anchors 21 that arematched with cage 12 in density have the most amount of holes orchannels compared to anchors 21 that are matched with cages 11 or 12.Anchors 21 can have the same indicia identifying their density level ascages 10, 11 and 12, therefore indicating which of cages 10, 11 or 12they match. In one embodiment, anchors 21 that are matched in densitywith cage 10 are located in a sealed package with cage 10. As describedabove, the sealed package can be green in color or have green markings.And anchors 21 that are matched in density with cage 11 are located in asealed package with cage 11. As described above, the sealed package canbe yellow in color or have yellow markings. And anchors 21 that arematched in density with cage 12 are located in a sealed package withcage 12. As described above, the sealed package can be red in color orhave red markings. This way it becomes more difficult to incorrectlymatch anchors 21 with the wrong counterpart cages 10, 11, or 12.

Anchors 21 are inserted through two upper holes 20 and two lower holes30 on cage 10, 11 and 12 so that each of cages 10, 11 and 12 has fouranchors, which can anchor the cage to a set of vertebrae in the spinalcolumn of a patient. Anchors 21 that are inserted through anchor holes20 are anchored to a first vertebra (superior), and anchors 21 that areinserted through anchor holes 30 are anchored or secured to a secondvertebra (inferior) that is inferior to the first vertebra. FIG. 3 is aside view that shows the orientation and angularity of the anchorsrelative to a cage, in this case cage 12, although the same is true withcages 10 and 11.

FIG. 4 shows an anchor of the present invention. When anchoring cages tovertebra, typically screws are used in the prior art. In the presentinvention, however, anchors 21 are used instead of screws. Anchors 21have multiple ridges 24 that drive into bone and secure anchors 21 tothe vertebral bone so that the anchors won't dislodge from the bone. Thehead of the anchor 22 can be struck to advance the distal end 23 ofanchor into bone and lodge anchor 21 into bone. In alternativeembodiments, screws instead of anchors 21 can also be used, althoughthey may not be as effective in long-term stability within the bone.

Anchor plate 40 is shown in FIG. 5. Anchor plate 40 has a bayonet lock42 that locks the anchor plate 40 to any one of cages 10, 11 or 12 whenthe bayonet lock 40 mates with an opening in the center of the faces ofcages 10, 11, and 12. This prevents any anchors 21 from falling out ordisassociating from cages 10, 11 or 12. Front face 41 of anchor plate 40can be tapped to engage and secure it to a cage 10, 11 or 12. Guideposts 43 are used to engage with guide holes in the faces of cages 10,11 or 12. Like anchors 21, anchor plate 40 can be matched to the densityof cages 10, 11 or 12. The interbody cage implants 10, 11, or 12 may notbe fusion implants that require anchoring, but may be cages that areimplanted without anchoring.

In one embodiment, each kit 1 contains one or more of the followingitems: (i) a sealed green colored package containing cage 10 (or 10 a),four anchors 21 that are matched in density with cage 10 (or 10 a), andan anchor plate 40 that is matched in density with cage 10; (ii) asealed yellow colored package containing cage 11 (or 11 a), four anchors21 (optional) that are matched in density with cage 11 (or 11 a), and ananchor plate 40 (optional) that is matched in density with cage 11 (or11 a); (iii) a sealed red colored package containing cage 12 (or 12 a),four anchors 21 (optional) that are matched in density with cage 12 (or12 a), and an anchor plate 40 (optional) that is matched in density withcage 12 (or 12 a); (iv) an inserter 13 that is used to insert one of thecages into a disk space between two adjacent vertebrae; (v) instructionsfor use; and (vi) bone graft material (optional).

The instructions for use of kit 1 can include the following steps foruse of the items found within kit 1:

-   -   i. determine the DEXA scan T-score of the patient's native bone        at the site of surgical intervention in the spine (this can be        done prior to the surgical procedure and be included in the        patient's medical records or chart and confirmed by the surgical        physician just prior to or during the surgical procedure;    -   ii. choose a cage from among the three cages 10, 11 or 12 (or 10        a, 11 a, or 12 a) that most closely matches the native bone's        BMD based on the DEXA scan T-score of the patient's native bone        at the site of implantation by doing the following:        -   1. If the patient's native bone has a DEXA Scan T-score of            −1 or higher, i.e., in the normal range of BMD indicated by            a T-score that is in the green range, retrieve the green            package containing cage 10 (or 10 a).        -   2. If the patient's native bone has as DEXA Scan T-score of            between −1 and −2.5, i.e., in the low range of BMD indicated            by a T-score that is in the yellow range, retrieve the            yellow package containing cage 11 (or 11 a).        -   3. If the patient's native bone has a DEXA Scan T-score            lower than −2.5, i.e., in the very low range of BMD            indicated by a T-score that is in the red range, retrieve            the red package containing cage 12 (or 12 a).    -   iii. Unseal the package that most closely matches your patient's        DEXA scan T-score as indicated above, and do NOT unseal the        other two sealed packages.    -   iv. Pack the bone graft material into the central hole B of the        cage (optional) that you retrieved.    -   v. Take the cage from the unsealed package, which now has bone        graft material in it (optional) and releasably couple it to the        inserter.    -   vi. Use the inserter to guide the cage into the disk space at        the site of intervention in the surgical procedure.    -   vii. Secure the cage within the spinal column using the four        anchors that are in the same sealed package (now unsealed) as        the cage that you used with this patient (optional).    -   viii. Secure the anchor plate over the exposed face of the cage        by inserting the bayonet lock of the anchor plate into the        opening on the face of the cage until it locks in place        (optional).    -   ix. Once the procedure is completed, discard kit 1.

Other embodiments of kits are also contemplated herein. For example, akit that doesn't contain anchors and the cages are self anchoring as aresult of being serrated or having other mechanisms that don't requireanchors. In other embodiments, the kits contain only one of theimplants, such as the most dense implant and not the others. In anotherembodiment, the kits contain two of the three implants set forth aboveand not all three implants. In another embodiment, the kits contain fouror more implants, including the three implants set forth above and atleast one more that is less dense than the least dense of the implantsset forth above.

The same principals discussed above with respect to interbody spinalfusion cages can be applied to other types of orthopedic implants, suchas knee implants and hip implants. In one embodiment, a hip implant kitis described, which contains at least three femoral stems, each havingouter dimensions that are virtually identical. However, they are not thesame weight, density, porosity, or surface area. The first one is themost dense, heaviest, least porous, and has the least surface area; thesecond is middle in density, porosity, weight and surface area; and thethird is the least dense, lightest in weight, most porous, and has themost surface area. The stems can be manufactured from implantable metal,plastic, reinforced plastic, titanium, titanium cobalt, stainless steel,cobalt-chromium alloys, titanium and cobalt mixed metal, ceramic, PEEKor carbon fiber, or any combination thereof. In one embodiment, they aremanufactured from titanium.

In one embodiment, each of the hip implant stems has identifying indiciathat indicates whether it is the most dense, middle density, or leastdense of the 3 stems. For example, the stems can be numbered 1, 2 and 3or the reverse etched into the stems. In another embodiment, theirdensity may be identified by a + − and = signs etched into the stems. Inanother embodiment, the stems may have a color painted on an area of thestem or the entirety of the stem. For example, the first stem that isthe most dense may be green; the second stem in middle density may beyellow; and the third stem with the least density may be red to matchthe typical DEXA Scan color coded results. In another embodiment, eachof the stems is located within a sealed package of its own that itselfhas an identifier that indicates whether it is the most dense, middledensity or least dense of the stems. For example, the first stem of thehighest density may be in a sealed package that is green or has greenmarkings on it; the second stem in middle density may be in a sealedpackage that is yellow or has yellow markings on it; and the third stemof lowest density may be in a sealed package that is red or has redmarkings on it. The purpose of this is so that the team of surgeons andstaff that are involved in a surgical procedure can easily identifywhich of the stems they should use based on the DEXA scan T-score of thepatient's hip, and they won't make a mistake by implanting the wrongstem.

In yet another embodiment, a kit contains 3 or more acetabularcomponents each having outer dimensions that are virtually identical.However, they are not the same weight, and they do not have the samedensity, porosity, or surface area. The first one is the most dense,heaviest, least porous, and has the least surface area; the second ismiddle in density, porosity, weight and surface area; and the third isthe least dense, lightest in weight, most porous, and has the mostsurface area. The acetabular components can be manufactured fromimplantable metal, plastic, reinforced plastic, titanium, titaniumcobalt, stainless steel, cobalt-chromium alloys, titanium and cobaltmixed metal, ceramic, PEEK or carbon fiber or any combination thereof.In one embodiment, they are manufactured from titanium.

In one embodiment, each of the acetabular components has identifyingindicia that indicate whether it is the most dense, middle density, orleast dense of the components. For example, the components can benumbered 1, 2 and 3 or the reverse etched into the components. Inanother embodiment, their density may be identified by a + − and = signsetched into the components. In another embodiment, the components mayhave a color painted on an area of the component or the entirety of thecomponent. For example, the first acetabular component that is the mostdense may be green; the second acetabular component in middle densitymay be yellow; and the third acetabular component with the least densitymay be red to match the typical DEXA Scan color coded results. Inanother embodiment, each of the acetabular components is located withina sealed package of its own that itself has an identifier that indicateswhether it is the most dense, middle density or least dense of thecomponents. For example, the first component of the highest density maybe in a sealed package that is green or has green markings on it; thesecond component in middle density may be in a sealed package that isyellow or has yellow markings on it; and the third component of lowestdensity may be in a sealed package that is red or has red markings onit.

In one embodiment, kit 1 is associated with a specific demographic. Forexample, it may be associated with white females, black females, whitemales, black males, Hispanic females, Hispanic males, Asian females,Asian males, or other demographics based on gender, race, ethnic origin,height, weight, physical condition, medications the patient takes,history of illness or current illness, or other factor for which theremay be a reference database for DEXA Scan T-scores. The specific kitthat most closely matches a patient can be used, because the cages inthat kit can have densities that are matched with the DEXA Scan T-scorereference database that most closely matches that patient in terms ofgender, race, ethnic origin, country of nationality or other factor.

Each of the kits described above can contain a instructions for useduring a surgical procedure on a patient. The instructions can containthe following steps, which are described with respect to a kitcontaining 3 or more implants of the same type but differentdensity/weight/surface area/porosity:

-   -   i. determine the DEXA scan T-score of the patient's native bone        at a site of surgical intervention in the spine (this can be        done prior to the surgical procedure and be included in the        patient's medical records or chart and confirmed by the surgical        physician just prior to or during the surgical procedure in        which an orthopedic implant is introduced into the patient;    -   ii. choose the implant from among the three implants that most        closely matches the native bone's BMD based on the DEXA scan        T-score;        -   1. If the patient has a DEXA Scan T-score of −1 or higher,            i.e., in the normal range of BMD indicated by a T-score that            is in the green range, choose the implant that has a green            indicia (or other indicia indicating highest density among            the three cages) or is in green packaging;        -   2. If the patient has as DEXA Scan T-score of between −1 and            −2.5, i.e., in the low range of BMD indicated by a T-score            that is in the yellow range, choose the implant which has a            yellow indicia (or other indicia indicating medium density            among the 3 cages) or is in yellow packaging;        -   3. If the patient has a DEXA Scan T-score lower than −2.5,            i.e., in the very low range of BMD indicated by a T-score            that is in the red range, choose the implant, which has a            red indicia (or other indicia indicating least density among            the three cages) or is in the red packaging.    -   iii. Introduce the implant to the patient's native bone at the        site of surgical intervention to the exclusion of the other two        implants.    -   iv. Once the procedure is completed, discard the kit.

In another embodiment, a method of treating a patient who requiressurgical implantation of an orthopedic implant is described. The methodincludes the steps of: determining the DEXA scan T-score of thepatient's native bone at a site of surgical implantation where theimplant will be in contact with the patient's native bone; choosing fromamong three or more otherwise identical implants an implant that has adensity that is closest to the density of the patient's native bone atthe site of surgical implantation based on the DEXA scan T-score of thepatient's native bone; and using said implant in the surgical procedureto the exclusion of the other two or more implants.

In one embodiment, the method of treatment involves implanting aninterbody spinal fusion cage in the spinal column. The physician ormedical team performing the surgery may determine the patient's gender,race and/or ethnic origin or this step may be skipped. The physician maydetermine other factors unique to the patient as well, such as height,weight, physical condition, the medications the patient takes, historyof illness or current illness. The physician or medical team performingthe surgery then determines the DEXA scan T-score of the native bone ateither or both the vertebra above and the vertebra below the locationwhere the cage will be implanted. Once the DEXA scan T-score isdetermined, the physician or medical team performing the surgery willchoose an interbody spinal fusion cage from among 3 or more cages thatmost closely matches the patient's DEXA scan T-score for either or bothof the vertebrae that were scanned relative to the other two implants.The DEXA scan T-score may use a general reference such as a healthyperson have peek bone at 30 years of age, or it may use a more specificreference, such as a black male. If a more specific reference is used,then a kit that is matched to that reference will be used rather than akit that is matched to a general reference. If the DEXA scan T-score isin the green range or a score of −1 or higher indicating healthy bone inthe normal range, then the cage having an indicia of highestdensity/weight and lowest surface area/porosity is chosen from among the3 or more cages. That indicia may be a number, a sign, or a color on thecage or on the packaging of the cage. For example, the cage may be in asealed package that is green or has green markings to indicate that itis the cage with the highest density/lowest porosity/greatestweight/lowest surface area. If the DEXA scan T-score is in the yellowrange or a score of between about −1 and about −2.5 indicating bone thatis lower than normal in density, then the cage having an indicia ofmedium density/porosity/surface area/weight is chosen from among the 3or more cages. Again, that indicia may be a number, a sign or a color onthe cage or on the packaging of the cage. For example, the cage may bein a sealed package that is yellow or has yellow markings to indicatethat it is the cage with the medium amount of density/porosity/surfacearea/weight from among the three or more cages. If the DEXA scan T-scoreis in the red range or a score of −2.5 or lower indicating very low bonedensity and osteoporosis, then the cage having an indicia of lowdensity/weight and high porosity/surface area is chosen from among the 3or more cages. Again, this indicia may be a number, sign or color on thecage or on the packaging of the cage. For example, the cage may be in asealed package that is red or has red markings to indicate that it isthe cage with the lowest density/weight and highest porosity/surfacearea from among the three or more cages. Once the physician or medicalteam has chosen the interbody cage based on the DEXA scan T-score of theparticular patient, that interbody cage is implanted in the spinalcolumn at the site of intervention to the exclusion of the other twocages. This process may be repeated for any further cages that are to beimplanted in the patient at other sites along the spinal column bymatching the correct cage with the site of intervention based on theDEXA scan T-score for the additional site(s) of intervention along thespinal column.

In another method of treating a patient requiring an orthopedic implant,the medical team treating the patient first obtains information aboutthe bone density of the patient's bone at the implantation site. Thebone density can be determined with a DEXA (sometimes referred to asDXA) scan providing a T-score for the bone at the implantation site.Once the medical team (physician, surgeon, etc.) knows the T-score orthe bone density of the bone at the implantation site as determined byDEXA scan or other means other than a DEXA scan, the medical teamselects an orthopedic implant that is close in density to the bone atthe site of implantation. The orthopedic implant has an identifierassociated with it that provides an indication of the density of theimplant. The identifier can indicate the actual density of theorthopedic implant or the relative density of the orthopedic implantcompared to other orthopedic implants of the same type. For example, theidentifier can indicate that a an interbody cage implant has a densityof 1.10 g/cm3 or greater as an absolute measure of density. Or theidentifier can indicate that among a number of interbody cage implants,the particular implant is more dense or less dense than other implantsof the same type. For example, when using color as an identifier, thecolor green color on the interbody cage (or associated with thepackaging of the interbody cage) may indicate that the interbody cage ismore dense than another interbody cage having the color yellow as itsidentifier or yet another interbody cage having the color red as itsidentifier. Thus, the colors, green, yellow and red may be indicators ofrelative density among the three implants. The green may indicate thatthe implant is closest in density to natural healthy bone; the yellowmay indicate that the implant is closest in density to bone having a lowbone mass; and the red may indicate that the implant is closest indensity to bone having the presence of osteoporosis; all relative to oneanother. In addition to, or in lie of the color identifier describedabove, the implant may have an identifier that is visible in an x-rayimage of the implant so that later x-ray scans of the patient canprovide information to the healthcare provider about the density of theimplant or other information about the implant. For example, outer wallsof the implants may have the identifiers DHD, DMD or DLD that arevisible in x-ray images of the implants and identify the implants asDexa High Density, Dexa Mid Density or Dexa Low Density respectively.

In one embodiment, if the bone of the patient at the site ofimplantation is healthy bone, the orthopedic implant selected by themedical team has about the same density as healthy natural bone having aT-score higher than −1.0 as measured by a DEXA scan (See FIG. 7). Theimplant has an identifier, such as the marking DHD visible in an x-rayimage of the implant, which identifies it as having a density that isabout the same as healthy natural bone having a T-score of −1.0 orhigher. This makes it easy and convenient for the medical team to knowthat the implant they are using has a density that is about the same asnatural healthy bone having a DEXA scan T-score of −1.0 or higher.Moreover, in later x-ray scans of the patient, healthcare providers cansee the marking and can identify the relative density or porosity of theimplant. The identifier can be a number, word, symbol, or color, such asthe marking DHD. In one embodiment, the identifier is a color, and thecolor is green, which is the color on a DEXA T-score chart thatcorresponds with healthy bone (see FIG. 7). Thus, the orthopedic implantitself can be entirely green, or a portion or part of it can be green,indicating that the density of the implant is about the same as naturalhealthy bone or bone having a DEXA scan T-score of −1.0 or higher. Thedensity of the implant having the green identifier can be about 1.10g/cm³ or greater, which generally corresponds with the density ofhealthy bone.

If the bone of the patient at the site of implantation has low bonemass, the orthopedic implant selected by the medical team has about thesame density as natural bone having a T-score of −2.5 to −1.0 asmeasured by a DEXA scan, which corresponds with bone having a low bonemass (See FIG. 7). The implant has an identifier, such as the markingDMD visible in an x-ray image of the implant, which identifies it ashaving a density that is about the same as natural bone having a lowbone mass and corresponding with a T-score of −2.5 to −1.0. This makesit easy and convenient for the medical team to know that the implantthey are using has a density that is about the same as the bone at thesite of implantation having the DEXA scan T-score of −2.5 to −1.0.Moreover, in later x-ray scans of the patient, healthcare providers cansee the marking and can identify the relative density or porosity of theimplant. The identifier can be a number, word, symbol, or color, such asthe marking DMD. In one embodiment, the identifier is a color, and thecolor is yellow, which is the color on a DEXA T-score chart thatcorresponds with low bone mass (see FIG. 7). Thus, the orthopedicimplant itself can be entirely yellow, or a portion or part of it can beyellow, indicating that the density of the implant is about the same asnatural bone having low bone mass or bone having a DEXA scan T-score of−2.5 to −1.0. The density of the implant having the yellow identifiercan be about 0.95 g/cm³ to about 1.10 g/cm³, which generally correspondswith the density of bone having a low bone mass but not necessarilyosteoporatic or having the presence of osteoporosis yet.

If the bone of the patient at the site of implantation has presence ofosteoporosis (i.e., is osteoporatic), the orthopedic implant selected bythe medical team has about the same density as natural bone having aT-score below −2.5 as measured by a DEXA scan, which corresponds withbone having a low bone mass (See FIG. 7). The implant has an identifier,such as the marking DLD visible in an x-ray image of the implant, whichidentifies it as having a density that is about the same as natural bonehaving the presence of osteoporosis and corresponding with a T-scorebelow −2.5 (See FIG. 7). This makes it easy and convenient for themedical team to know that the implant they are using has a density thatis about the same as the osteoporatic bone at the site of implantationhaving the DEXA scan T-score below −2.5. Moreover, in later x-ray scansof the patient, healthcare providers can see the marking and canidentify the relative density or porosity of the implant. The identifiercan be a number, word, symbol, or color, such as the marking DLD. In oneembodiment, the identifier is a color, and the color is red, which isthe color on a DEXA T-score chart that corresponds with the presence ofosteoporosis (see FIG. 7). Thus, the orthopedic implant itself can beentirely red, or a portion or part of it can be red, indicating that thedensity of the implant is about the same as natural bone having thepresence of osteoporosis or bone having a DEXA scan T-score of below−2.5. The density of the implant having the red identifier can be belowabout 0.90 g/cm³′ such as between about 0.60 gm/cm³ and about 0.95 g/cm³or lower, which generally corresponds with the density of bone havingthe presence of osteoporosis.

Thus, if the patient's bone at the site of implantation is normalhealthy bone, the medical team will select the orthopedic implant withthe green identifier (or other identifier, such as the marking DHDvisible in an x-ray image) and implant that at the site of implantation.If the patient's bone at the site of implantation has low bone mass, themedical team will select the orthopedic implant with the yellowidentifier (or other identifier, such as the marking DMD visible in anx-ray image) and implant that at the site of implantation. If thepatient's bone at the site of implantation has presence of osteoporosis,the medical team will select the orthopedic implant with the redidentifier (or other identifier, such as the marking DLD visible in anx-ray image) and implant that at the site of implantation. When thepatient is undergoing a spinal procedure and requires an interbody cageimplanted in between successive vertebrae, the implant can be aninterbody cage or, alternatively, an interbody cage for spinal fusion.Interbody cages are placed between the bodies of 2 adjacentvertebrae—after removing the intervertebral disc that typically occupiesthis space. Interbody cages may be made of metal, polymer, ceramic, or afusion of different materials. Two commonly used materials includetitanium and polyetheretherketone (PEEK). The interbody cage can becoated with various materials, such as TiNANO®, a titanium plasma spraycoating. The interbody cage will typically have a hollow center (such asshown in FIGS. 1 and 8), which is filled with a bone-growth promotingmaterial, such as beta-tricalcium phosphate or the patient's own bonetaken from a another location of the patient's skeletal anatomy. Theinterbody cage can also be expandable—a small cage is implanted(reducing the risk of nerve injury), which expands to a larger sizeafter the implantation is done. The medical team can typically controlthe extent of expansion, to ensure that the surrounding nerves are notinjured during the surgery. The interbody cage can be any size andvariation described here or known in the art. However, the density ofthe interbody cage that is implanted will depend on the density of thepatient's bone at the site of implantation as described here.

Another embodiment of the invention relates to orthopedic implants thatare marked with information or data that is visible in an x-ray image.The data or information that is marked onto the implant can relate toinformation about the patient or can be a data or time, such as the dateand/or time of implantation. It can be information about the type ofimplant, the density or porosity of the implant itself, such asdescribed above with respect to interbody cage implants, or any otherinformation that may be useful for the patient or the patient'shealthcare provider in the future, when the patient is x-rayed. Themarking may be from the same material as the rest of the implant,however it may be more dense or more solid or less dense or less solidthan the rest of the implant, making it stand out in an x-ray image ofthe implant. In one embodiment, as described above, the informationmarked on the implant indicates the relative density or porosity of theimplant as it relates to BMD of the bone of the patient at the site ofimplantation.

While the is susceptible to various modifications and alternative forms,specific examples thereof have been shown by way of example in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the appended claims.

We claim:
 1. An interbody cage implant that has about the same densityas natural bone that has a T-score above −1.0 as measured by a DEXAscan, and wherein the interbody cage implant has an identifier thatidentifies it as having a density that is about the same as natural bonehaving a T-score above −1.0, wherein the interbody cage implant isframeless.
 2. The interbody cage implant of claim 1, wherein theinterbody cage implant has a density of about 1.10 g/cm³ or greater. 3.The interbody cage implant of claim 1, wherein the identifier is thecolor green.
 4. The interbody cage implant of claim 3, wherein theentire interbody cage implant is green.
 5. The interbody cage implant ofclaim 3, wherein a portion of the interbody cage implant is green.
 6. Aninterbody cage implant that has about the same density as natural bonethat has a T-score of −2.5 to −1.0 as measured by a DEXA scan, andwherein the interbody cage implant has an identifier that identifies itas having a density that is about the same as natural bone having aT-score of between −2.5 and −1.0, wherein the interbody cage implant isframeless.
 7. The interbody cage implant of claim 6, wherein theinterbody cage implant has a density of between about 0.95 g/cm³ andabout 1.10 g/cm³.
 8. The interbody cage implant of claim 6, wherein theidentifier is the color yellow.
 9. The interbody cage implant of claim8, wherein the entire interbody cage implant is yellow.
 10. Theinterbody cage implant of claim 8, wherein a portion of the interbodycage implant is yellow.
 11. An interbody cage implant that has about thesame density as natural bone that has a T-score below −2.5 as measuredby a DEXA scan, and wherein the interbody cage implant has an identifierthat identifies it as having a density that is about the same as naturalbone having a T-score below −2.5, wherein the interbody cage implant isframeless.
 12. The interbody cage implant of claim 11, wherein theinterbody cage implant has a density less than about 0.95 g/cm³.
 13. Theinterbody cage implant of claim 11, wherein the identifier is the colorred.
 14. The interbody cage implant of claim 13, wherein the entireinterbody cage implant is red.
 15. The interbody cage implant of claim13, wherein a portion of the interbody cage implant is red.
 16. A methodof treating a patient in need of an interbody cage implant, the methodcomprising: selecting an interbody cage implant that has about the samedensity as the native bone at the site of implantation, wherein theinterbody cage implant is frameless; and implanting the orthopedicimplant at the site of implantation.
 17. The method of claim 16, whereinthe interbody cage implant forms a lattice structure that mimicscancellous bone.
 18. The method of claim 17, wherein the interbody cagecomprises an identifier to indicate its density.
 19. The method of claim18, wherein the identifier is the color green if the density of theinterbody cage is about the same as normal healthy bone at the sight ofimplantation.
 20. The method of claim 19, wherein the interbody cage hasa density of about 1.10 g/cm³ or greater.
 21. The method of claim 19,wherein the entire interbody cage is green.
 22. The method of claim 19,wherein a portion of the interbody cage is green.
 23. The method ofclaim 18, wherein the identifier is the color yellow if the density ofthe interbody cage is about the same as bone having a low bone mass atthe site of implantation.
 24. The method of claim 23, wherein theinterbody cage has a density of between about 0.95 g/cm³ and about 1.10g/cm³.
 25. The method of claim 23, wherein the entire interbody cage isyellow.
 26. The method of claim 23, wherein a portion of the interbodycage is yellow.
 27. The method of claim 18, wherein the identifier isthe color red if the density of the interbody cage is about the same asbone having the presence of osteoporosis at the site of implantation.28. The method of claim 27, wherein the interbody cage has a densityless than about 0.95 g/cm³.
 29. The method of claim 27, wherein theentire interbody cage is red.
 30. The method of claim 27, wherein aportion of the interbody cage is red.
 31. The method of claim 16,further comprising the step of ascertaining the BMD of the patient'snative bone at the site of implantation, wherein the BMD is determinedusing a bone density test.
 32. The method of claim 31, wherein the bonedensity test is an x-ray scan, a DEXA scan, or a CT scan.
 33. The methodof claim 32, wherein the bone density test is a DEXA scan, and the BMDof the patient's native bone at the site of implantation is representedby a T-score.
 34. The method of claim 33, wherein the orthopedic implantis an interbody cage.
 35. The method of claim 34, wherein the interbodycage comprises an identifier to indicate its density.
 36. The method ofclaim 35, wherein the identifier is the color green if the density ofthe interbody cage is about the same as bone having a T-score above −1.0at the sight of implantation.
 37. The method of claim 36, wherein theinterbody cage has a density of about 1.10 g/cm³ or greater.
 38. Themethod of claim 36, wherein the entire interbody cage is green.
 39. Themethod of claim 36, wherein a portion of the interbody cage is green.40. The method of claim 35, wherein the identifier is the color yellowif the density of the interbody cage is about the same as bone having aT-score between −2.5 and −1.0 at the site of implantation.
 41. Themethod of claim 40, wherein the interbody cage has a density of betweenabout 0.95 g/cm³ and about 1.10 g/cm³.
 42. The method of claim 40,wherein the entire interbody cage is yellow.
 43. The method of claim 40,wherein a portion of the interbody cage is yellow.
 44. The method ofclaim 35, wherein the identifier is the color red if the density of theinterbody cage is about the same as bone having a T-score below −2.5 atthe site of implantation.
 45. The method of claim 44, wherein theinterbody cage has a density less than about 0.95 g/cm³.
 46. The methodof claim 44, wherein the entire interbody cage is red.
 47. The method ofclaim 44, wherein a portion of the interbody cage is red.
 48. Theinterbody cage implant of claims 1 and 11, wherein the identifier isvisible in an x-ray image of the implant.